Dawsonbob... you can get many rocks to spark by hitting them together. Anything with quartsite is excellent. However it is a different kind of spark caused by the compression and I believe its electrical (but i'm not sure, exactly) These types of sparks don't burn like iron shards and can't transfer heat to you tinder. Perhaps you are located in an iron pyrite rich area. But hitting two pieces of quartz together won't light your fire.
I won't even begin to talk about the kind of tinder prep you need for that. What kind of tinder are you using, anyway?
Sorry if I'm coming off like a prick... but I'm very interested in your method... if not to rub it in Bow's nose... he he
Rick
Rick, I'm sure that there is pyrite around here (San Diego), but I've never found a big chunk of it. On the other hand, there's lots of various quartzite type rocks here, many of which may contain pyrite. I don't know for sure, since I'm not really a rock guy. I just wander around and find different types of rocks and bang them together to see what happens. Sometimes nothing happens at all. Other times it will flake off into a blade of one sort or another, but
sometimes they'll produce a pretty good spark.

I think the effect you're thinking of is a piezoelectric spark: you know, the exact same one that's used in many butane lighters.
You're right: two stones don't throw the exact same kind of spark as flint and steel, but sometimes they throw one just as good. Maybe there's iron in some of the stones: I don't know. I do know, however, that sparks come off that last long enough to light tinder. Maybe it hasn't worked for you yet, but it does work. People have been using this method for thousands of years. Yes, flint and steel are more consistently reliable, but don't give up on the stones: they do work — I know; I've done it myself (not in many years though).
As far as tinder, I used cattail fluff if I remember correctly, but I'm sure other tinder would work as well, if not better.
Now you've got me wanting to get out and do it again. Unfortunately, the truck has a blown head gasket, so I'm not going anywhere for awhile. If I ever find the money to get it fixed though, I'll be out banging rocks for you. I don't have a video camera, so you'll have to settle for stills.
You're not coming off as a pr**k, just as a pushy bastid.
